358 THE CANADIAN ENTOMOLOGIST 



peculiar, droning, buzzing whirr, and may be heard for long dis- 

 tances. So different are these notes that the writer was con- 

 vinced he had captured another species. During the summer 

 of 191?"), several individuals of both groups were taken. Although 

 it was first thought that those individuals characterized by the 

 stronger note were generally larger and possibly came closer to 

 N. robustus robtisius, it was finally decided to refer all to the form 

 N. robustus crepitans. 



The ciucstion is not solved, however, and needs further in- 

 vestigation. Such well marked differences cannot possibly be 

 associated witli temperature relations, as the two stridulations 

 may be heard in the same \icinity at the same time. The stronger 

 note is far less commonly heard. Occasionalh-, stridulations 

 somewhat intermediate between the two extremes may be 

 heard . 



Rejin and Hebard* find that the A', robustus robustus and 

 N. robustus crepitans intergrade within very narrow limits (Ocean 

 View, New jersey; and Philadelphia, Pennsylvania) although 

 intermediate material has been found as far south as the District 

 of Columbia. It is interesting to note that Davis has noted 

 differences in the stridulations of the two forms; the stridulations 

 of robustus appearing to be louder than the stridulations of crepitans. 

 Rehn and Hebard have noted a day song, or "sleep-song", for 

 N. robustus robustus. They say: "This day song, or what might 

 well be termed, sleep song, is in reality a brief and drowsy impulse 

 giving just sufficient energy to the act of stridulation to demon- 

 strate the sound produced when the vibrations are not at full 

 speed, the irregularity of the sound resulting from the same cause." 

 The writer has noted a similar drowsy, half-hearted day song 

 in the case of Neoconocephalus retusus (Scudder). 



It would be very interesting to determine to what extent 

 hybridization could be brought about between typical forms of 

 robustus and crepitans. It is possible that hybrid material would 

 throw much light upon the exact status of these forms. 



* "A synopsis of the Species of the Genus Neoconocephalus found in 

 North American North of Mexico." Trans, of the Am. Ent. Soc. Vol. XL, 

 No. 4, p. ;565-413. 



